In some communication systems, a mobile communication terminal receives downlink signals from a base station over a communication channel, and sends feedback indicative of the communication channel to the base station. The base station configures subsequent transmissions based on the feedback. Channel feedback of this sort is used, for example, in Evolved Universal Terrestrial Radio Access (E-UTRA) systems specified by the 3rd Generation Partnership Project (3GPP). These systems are also referred to as Long Term Evolution (LTE) and LTE Advanced (LTE-A).
Channel feedback schemes for LTE and LTE-A systems are discussed, for example, in 3GPP Technical Specification Group Radio Access Network Working Group 1 (TSG-RAN WG1) document R1-104473, entitled “Way Forward on 8Tx Codebook for Rel. 10 DL MIMO,” Madrid, Spain, Aug. 23-27, 2010; in 3GPP TSG-RAN WG1 document R1-105067, entitled “Way Forward on CSI Feedback for Rel. 10 DL MIMO,” Madrid, Spain, Aug. 23-27, 2010; in 3GPP TSG-RAN WG1 document R1-103839, entitled “Design and Evaluation of Precoder Codebooks for CSI Feedback,” Dresden, Germany, Jun. 28-Jul. 2, 2010; and in 3GPP TSG-RAN WG1 document R1-104353, entitled “Two-Component PMI Codebook for 8TX,” Madrid, Spain, Aug. 23-27, 2010, which are all incorporated herein by reference.
The description above is presented as a general overview of related art in this field and should not be construed as an admission that any of the information it contains constitutes prior art against the present patent application.